The only thing that brought the two countries together was getting one over the USSR. Divide and conquer is the oldest trick in the book. After that, China threatening the US's top spot as economic superpower made them the bad guys. The US hates competition unless it drives down worker wages.
Ehh idk. Whoever thinks that China will take the top spot hasn’t checked China’s demographic pyramid. They’ll likely make a push for Taiwan in the next five years not because they’re finally militarily ready, but because if it doesn’t happen soon, it certainly won’t happen later on when the country is struggling to maintain the status quo internally.
The demographics issue is overblown and often gets repeated uncritically with a bunch of assumptions. I guess we'll wait and see. What's definitely true is that based on current trajectory, China is poised to take the top spot.